Development of electric vehicles has become a trend in future development of the automotive industry and large-scale connection of electric vehicles to the grid will necessarily affect the entire power system such that remote control over charging and discharging activities of numerous distributed electric vehicles becomes an inevitable choice for the power system when dealing with the relation of interests between popularization and regulation of electric vehicles.
The efficient implementation of charging and discharging functions of an electric vehicle deemed as a special mobile energy storage unit via reasonable control of a convertor in a charging facility can largely meet requirements for power frequency modulation, backup services and distributed power source and electrical energy consumption services, etc. in the wide-area power system and is of great significance for improvement of overall electrical energy quality of the power system and cost reduction for electric vehicle holders.
From the perspective of a vehicle-mounted power battery, over-charging and -discharging will both affect the life of the battery while causing a waste of electrical energy of the grid. Therefore, it is necessary to monitor the state of charge of a battery, reasonably distribute the total power demand in the wide-area power system, and to perform dynamic control on charging and discharging of the battery.
Currently available documents only regard electric vehicles as a special type of batteries and perform local control thereon, without considering interaction among a generator set, the grid and electric vehicles in the wide-area power system or taking dynamic matching relations between the charging and discharging and the generator set of electric vehicles into account, and thus they do not conform to actual conditions of the power system and have no strong practicality.